XIRR vs IRR in Excel

IRR and XIRR both find the discount rate that makes the net present value of a series of cash flows equal zero. IRR assumes equally spaced periods, while XIRR uses the actual date of each cash flow. For real investments with irregular timing, capital calls, and distributions, XIRR gives the accurate annualized return and is the standard in finance.

The difference between IRR and XIRR

=IRR(values, [guess]) assumes each cash flow occurs at the end of an equal period and returns the per period rate. If your periods are months, the result is a monthly rate that you must annualize yourself.

=XIRR(values, dates, [guess]) pairs each cash flow with a real date and returns an annualized rate directly, accounting for the exact number of days between flows. Because it uses dates, it handles uneven timing, partial periods, and capital that goes in and out on arbitrary days, which is the norm in fund and deal returns.

Requirements both functions share

Both functions need at least one negative and one positive cash flow, otherwise they return a #NUM! error, because there must be both an outflow and an inflow for a return to exist.

Both solve iteratively and accept an optional guess. If the function cannot converge it returns #NUM!, and supplying a guess close to the expected rate (for example 0.1 for 10 percent) helps it find the answer. For XIRR, the first date in the list is treated as the start, and the other dates may be in any order as long as each aligns with its cash flow.

Worked example: irregular distributions

Suppose you invest -10000 on 1 Jan 2025, receive 3000 on 15 Apr 2025, and receive 9000 on 30 Nov 2025. The intervals are clearly unequal.

1. Put the cash flows in C2:C4 (-10000, 3000, 9000) and the dates in D2:D4 (the three dates above).
2. Enter =XIRR(C2:C4, D2:D4). XIRR returns the annualized return using the actual days between each flow.
3. Trying =IRR(C2:C4) here would be wrong, because IRR assumes the three flows are one equal period apart, which they are not.
4. Add an optional guess, =XIRR(C2:C4, D2:D4, 0.1), if the function returns #NUM! and fails to converge.

Unequal day gaps make XIRR correct and plain IRR misleading here.

Which to use

Use XIRR for almost all real return work: private equity and venture cash flows, irregular dividends, loan schedules, and any analysis where cash moves on actual calendar dates. It is the convention because it returns a directly comparable annualized figure.

Reserve IRR for clean, equally spaced series such as a tidy annual or monthly model with no date gaps, and remember to annualize a per period IRR yourself. When in doubt, attach dates and use XIRR, since it reduces to the same answer as IRR when the periods happen to be equal.